Residential fuel oil and propane distribution requires the delivery of fuel from a distribution center, typically operated by a local fuel delivery company, to each residence. On average, seven trips are made per customer per year.
There are costs to the fuel company for each trip, including the fuel truck driver's salary and costs of maintaining the truck. Yet, while the average oil tank size is 275 gallons in the United States, the average delivery is less than 125 gallons. Propane delivery efficiency, with the common 1000 gallon tanks, is even less than heating oil. Thus, many more trips are being made per year than necessary, impacting the profitability of the oil and propane delivery companies and consequently the costs of the fuel to the consumer.
Despite the fact that the average delivery is made when the tank is more than one half full, “run outs” are also common. When a run out occurs, the customer's home is usually no longer heated. In the best case, a special trip is necessary to deliver new fuel and re-light the furnace. Often, lines need to be purged and pilot lights re-lit in the event of a run out. This adds additional cost to the fuel delivery company that may not be recoverable from the customer. Moreover, if the customer is not at home during the run out, the home's water pipes can freeze and burst—causing avoidable repairs.
Many systems have been devised to solve these problems. The most prevalent of the present solutions is the “Degree Day” system. This is a system that measures the outside temperatures and past usage to predict when the next delivery should be made. This system, however, has drawbacks: it assumes that past usage patterns will continue; and new customers cannot be served because there are no past usage data. The system also assumes a number for the rate of usage related to average daily temperatures, and the system cannot function properly with any data entry error. At best, the Degree Day system is an approximation of the customer's fuel needs.
Other systems have been devised to directly measure the tank volume and then use this information in the scheduling of fuel delivery. Various level sensors have been proposed such as float systems or ultrasonic devices. The homeowner may then monitor the sensor and call the delivery company when the fuel level is low. Other systems propose to automatically communicate tank level information to the fuel delivery company such as via the cellular telephone network.